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Consider the Shape and Number of Blades
What turns the blades of a wind turbine?
When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag and this causes the rotor to spin.
This blade shows that the cross section has a streamlined asymmetrical (uneven) shape. The flattest side of the blade faces the oncoming wind. See this movie that explains this design: New Blade Design for Wind Turbine.
According to https://www.turbinesinfo.com, "a blade designer does not merely sit down and outline the shape when designing a new blade. The shape must be chosen with great care on the basis of past experience. For this reason blade profiles were previously chosen from a widely used catalogue of airfoil profiles developed in wind tunnel research by NACA (The United States National Advisory Committee for Aeronautics) around the time of the Second World War."
A modern wind turbine blade is similar to the wings of an airplane. Airplane wings are very aerodynamic, able to let wind pass by at very high speeds.
Wind turbine blades have been designed in many different shapes. Today blades of modern wind turbines are lighter than older wind turbines so they can accelerate quickly at lower wind speeds.
The diagram shows a cross-cut section of a wind turbine blade with air flowing over it and air coming from below, you can see that the blade has one flat side and one more rounded side.
Lift and drag forces on wind turbine blades can be explained on this YouTube video:
Most HAWTs (horizontal axis wind turbines) will have two to three blades. Most vertical axis wind turbines will usually have two or more blades.
The blades of the Vertical Axis Wind Turbine (VAWT) catch wind in any direction without directional orientation. This makes it ideal for gusty conditions.
The Vertical Axis Wind Turbine (VAWT) is one type of turbine that can be constructed. Watch this video to learn how they operate.
Here is another video about Harmony VAWTs:
Watch this movie to learn one way to construct a Vertical Axis Wind Turbine (VAWT).
As air flows past the blade (aerofoil), the air separates, with half of the air moving over the more curved side of the blade, and half of the air moving over the less cureved side of the blade. The air traveling over the more curved side stretches causing the air molecules to move apart as the travel over a longer distance than the air traveling over the less curved side of the blade. In order for the air molecules to meet up again on the other side of the blade at the same time, the air traveling over the more curved side travels faster since it has a further distance to travel. This creates lower air pressure on the more curved side and higher air pressure on the less curved side. The higher air pressure pushes against the blade. Because the blade is attached to the hub, this high air pressure makes the blade spin around the hub.
This movie explains how wind turbine blades work by generating lift due to their curved shape. It also shows how to make blades with curved side and less curved side from PVC material and hand tools. Look at the movie from 5:10 minutes to 6:48 minutes to learn now the turbine blade relates to an airplane wing.
How does a wind turbine generate power? BluEarth Renewables Inc.'s movie gives with a basic overview of wind turbines and how they generate electricity.
What is electricity? Electricity is a basic part of nature and it is one of our most widely used forms of energy and is caused by tiny, negatively-charged particles known as electrons. Electricity is the flow of electrons. When electricity builds up in one place, scientists call it static electricity. When it moves from one place to another, it's called current electricity. Electric currents power all of those electronic devices we've come to depend on such as powering our TVs, toasters, refrigerators, and so on. Read this explanation from Wonderopolis about how electricity is formed and works.
Wind Turbine Walls
Wind Turbine Walls
Joe Doucet and his partners designed several different wind turbine walls that produce electricity that is stored in a wall-mounted battery. These wind turbine walls (also called kinetic walls) not only produce enough energy for a home or business, but they are also aesthetically pleasing! Read more: https://kottke.org/21/10/wind-turbine-wall
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